Fig. 5

Predictive modeling based on univariate and multivariate logistic regression analysis of variables involved in fixation loosening in vertical FNF. A Predictive nomogram estimates of risk factors from the multivariate logistic regression analysis. B Using the bootstrap method, a calibration plot was constructed to compare the predicted outcome of fixation loosening to the actual outcome. C Area under the receiver operating characteristic curve for the predictive performance of risk factors for fixation loosening in vertical FNF was 0.868 (0.800–0.936), indicating strong predictive ability